Is Martin Luther King a platonist?

King was certainly well-versed in the classics as well as modern philosophy. He frequently quoted from contemporary religious scholars, ancient authorities, and many others who were at least influenced by Platonism. In his famous "Letter from a Birmingham Jail," King quoted St. Augustine, who was himself profoundly influenced by Plato, in addressing concerns over his approach to civil disobedience, saying "I would agree with St. Augustine that 'An unjust law is no law at all.'" He went on to argue, quoting Thomas Aquinas, that temporal laws must be connected to natural laws, which he saw as just. These natural laws were eternal, immutable, and inextricably connected to human existence. In this, he followed Plato, who saw justice as an eternal form that could only be ascertained through philosophy. For Plato, justice was not negotiable, historically contingent, nor situational. When King argued that the "arc of moral history is long, but it bends toward justice," he was casting justice as an ideal, divinely created form that people, through their actions, were aspiring to reach. To the extent that social institutions deviated from this ideal, it was the duty of people to correct them through their actions. So there certainly is a sense in which Martin Luther King Jr. was a Platonist.
https://plato.stanford.edu/entries/augustine/

https://www.theatlantic.com/magazine/archive/2018/02/letter-from-birmingham-jail/552461/